P246D: Ford DPF pressure sensors disagree under exhaust flow

P246D is particulate-filter pressure sensor A/B correlation. In Ford's 2015 diesel summary, the controller compares pressure indicated by the DPFP and DPS sensors. An absolute difference greater than 1.5 kPa is the listed failure criterion, with a typical two-second evaluation.

Compare under the required conditions

The documented check needs warm coolant, pre-DPF temperature between 125°C and 425°C, and exhaust flow between 200 and 600 kg per hour. It also includes environmental pressure and temperature limits. A key-on reading with no exhaust flow is therefore not the same test opportunity.

The DPS is described as a dual-port sensor measuring pressure drop across the filter. Its electrical high- and low-range checks are separate from P246D's agreement test.

Disagreement does not identify the bad side

The code establishes a mismatch between two pressure indications. It does not automatically prove that the filter is restricted, nor does it identify which measurement path is inaccurate. Preserve both values and the exhaust-flow conditions. The applicable pressure-sensor and hose diagnostic procedure must isolate the cause before a sensor or filter is replaced. Work around hot exhaust and pressure connections requires the vehicle's specified precautions.

Source and applicability

Ford 2015 model-year diesel OBD system operation summary, revision December 22, 2014; the cited monitor only, without blanket model or engine applicability. Ford source, physical PDF page 133. The documented monitor explains the fault decision; vehicle-specific service information is still needed for connector identification and a complete repair procedure.